1. Field of the Invention
The present invention relates to a tank for containing liquid.
2. Description of the Related Art
An autonomous running and working robot having a tank containing cleaning liquid provided on its body, which runs while applying liquid to the floor surface has been proposed. Liquid dispensing opening of the tank is provided at a bottom surface of the tank, and a valve having similar structure for a tank used for an oil stove has been known. By placing the tank at a tank receiving portion of the autonomous running and working robot, the liquid contained in the tank flows out of the tank through the liquid dispensing opening. The emitted liquid can be applied to the floor surface by a working unit designed therefor.
However, liquid such as water used for cleaning by the autonomous running and working robot has high surface tension. Therefore, the liquid does not flow out from the liquid dispensing opening unless the liquid dispensing opening is adapted to have considerably large opening area. However, if the opening area of the liquid dispensing opening is increased, the valve itself becomes larger, degrading sealing property.